Vehicle seat

ABSTRACT

A vehicle seat includes a seat back, and an airbag that deploys in the seat back. The airbag deploys in the seat back in such a way that, after having deployed, the airbag elastically supports an upper body of an occupant and elastically receives an impact force applied to a back surface of the seat back. After having deployed, the airbag has such a shape that a deployment amount, in a front-back direction, of the airbag near a side of the seat back is greater than that near a center of the seat back.

The present application is a Divisional Application of U.S. patentapplication Ser. No. 14/502,727, filed on Sep. 30, 2014, which is basedon and claims priority from Japanese Patent Application No. 2013-206797,filed on Oct. 1, 2013, the entire contents of which are incorporatedherein by reference.

BACKGROUND 1. Technical Field

The present invention relates to a vehicle seat, and, in particular, toa vehicle seat including a seat back and an airbag disposed in the seatback.

2. Related Art

Regarding vehicle seats of automobiles or the like, airbag systems areknown that protect an occupant in a vehicle seat from an impact of acollision by deploying an airbag disposed in a seat back.

For example, Japanese Unexamined Patent Application Publication (JP-A)10-273000 describes a vehicle seat including a seat back frame, anelastic support member extending across the seat back frame, a seat paddisposed on a front surface of the elastic support member, a supportplate disposed behind the elastic support member and having a rigidstructure, and an airbag in a deflated state disposed in a space betweenthe elastic support member and the support plate.

With the vehicle seat, when an impact of a predetermined level orgreater is detected, an inflator is activated to deploy the airbagbetween the elastic support member and the support plate. Thus, during acollision, the airbag elastically supports backward movement of anoccupant from behind and restrains the occupant, and absorbs the impactenergy by being depressurized and deflated.

JP-A 2010-52621 describes an airbag device including a first airbag anda second airbag. The first airbag is disposed in a lower back part of aseat back of a front seat and deploys toward an occupant in a rear seat.The second airbag, which is in a flat state, is disposed in a space inthe seat back of the front seat, the space being on the front side of anelastic support member extending across a seat back frame.

Thus, when an impact of a predetermined level or greater is detected, aninflator is activated to deploy the first airbag toward an occupant inthe rear seat. Therefore, even if the occupant in the rear seat is movedforward by an impact during a collision, the occupant is prevented fromstrongly colliding with the back surface of the front seat. Moreover,the second airbag deploys so as to elastically support backward movementof the upper body of an occupant in the front seat during a collisionfrom behind and protects the occupant. The timings at which the firstand second airbags are deployed are controlled so as to appropriatelyprotect the occupants.

As described above, the vehicle seat described in JP-A 10-273000protects an occupant in the vehicle seat by using an airbag and asupport plate, which is disposed behind and outside of the airbag andwhich has a rigid structure. To be specific, the airbag alleviates animpact due to backward movement of the occupant, and the support platefirst receives an impact exerted from behind the seat back and then theairbag absorbs the impact.

Accordingly, in a case where the vehicle seat is a front seat, if anoccupant in a rear seat collides with the front seat from behind theseat back, a considerable impact is generated when the occupant collideswith the support plate. Accordingly, an impact from behind might not begently received, and therefore not only may the occupant in the rearseat receive considerable damage to a knee or the like but also theoccupant in the front seat may receive a considerable impact.

On the other hand, the airbag device described in JP-A 2010-52621 canprotect an occupant in a front seat and reduce damage to the occupantbecause the second airbag deploys in the seat back of the front seat.Moreover, the airbag device can protect an occupant in a rear seatbecause the first airbag deploys toward the occupant in the rear seat.However, it is necessary not only to provide the second airbag in theseat back but also to provide the first airbag, which deploys backwardand outward from the seat back, in the lower part of the seat back ofthe front seat. Therefore, the structure of the seat back becomescomplex, and it becomes difficult to control the airbags.

Moreover, because the first airbag deploys by a large amount in adirection diagonally upward from a lower back part of the seat back ofthe front seat toward an occupant in the rear seat, the deployment shapeof the first airbag becomes unstable. Therefore, the airbag device mightnot be able to stably and reliably receive and absorb an impact extortedon the occupant in the rear seat when the occupant collides with theseat back of the front seat.

As described above, in each of the structures of the related artdocuments, there is room for improvement in directly protecting anoccupant in the front seat and protecting the occupant from an impactexerted from behind the seat back by using an airbag and a simplestructure.

Note that, in vehicles, such as automobiles, a collision of a knee orthe like of an occupant in a rear seat with the seat back of a frontseat may occur not only during a frontal collision but also during arear-end collision in the following situation: a situation where a rearpart of the vehicle body becomes deformed during a rear-end collisionand an occupant in a rear seat is pushed forward due to the deformationand a knee of the occupant strongly collides with the back surface ofthe seat back of the front seat.

SUMMARY OF THE INVENTION

The present invention provides a vehicle seat that can directly protectan occupant by using an airbag and that can reliably reduce an impactexerted on the occupant from behind a seat back during a collisionwithout using a complex structure.

A first aspect of the present invention provides a vehicle seatincluding a seat back, and an airbag that deploys in the seat back. Theairbag deploys in the seat back in such a way that, after havingdeployed, the airbag elastically supports an upper body of an occupantand elastically receives an impact force applied to a back surface ofthe seat back. After having deployed, the airbag has such a shape that adeployment amount, in a front-back direction, of the airbag near a sideof the seat back is greater than that near a center of the seat back.

After having deployed, the airbag may have such a shape that adeployment amount, in the front-back direction, of the airbag near anouter side of a vehicle is greater than that near an inner side of thevehicle.

After having deployed, the airbag may have such a shape that adeployment amount, in the front-back direction, of the airbag near aninner side of a vehicle is greater than that near an outer side of thevehicle.

A second aspect of the present invention provides a vehicle seatincluding a seat back, and an airbag that deploys in the seat back.After having deployed, the airbag has such a shape that a deploymentamount, in the front-back direction, of the airbag near an upper part ofthe seat back differs from that near a lower part of the seat back. Theairbag deploys in the seat back in such a way that, after havingdeployed, the airbag elastically supports an upper body of an occupantand elastically receives an impact force applied to a back surface ofthe seat back.

After having deployed, the airbag may have such a shape that adeployment amount, in the front-back direction, of the airbag near anupper part of the seat back is greater than that near a lower part ofthe seat back.

After having deployed, the airbag may have such a shape that adeployment amount, in the front-back direction, of the airbag near alower part of the seat back is greater than that near an upper part ofthe seat back.

After the airbag has deployed, the back surface of the airbag may havean undulating shape that allows the airbag to restrain and hold animpact applying member that applies an impact force to the back surfaceof the seat back.

An third aspect of the present invention provides a vehicle seatincluding a seat back, and an airbag that deploys in the seat back. Theairbag deploys in the seat back in such a way that, after havingdeployed, the airbag elastically supports an upper body of an occupantand elastically receives an impact force applied to a back surface ofthe seat back. After having deployed, the airbag has such a shape that adeployment amount, in a front-back direction, of the airbag near a frontside of the seat back is greater than that near a back side of the seatback.

A fourth aspect of the present invention provides a vehicle seatincluding a seat back, and an airbag that deploys in the seat back. Theairbag deploys in the seat back in such a way that, after havingdeployed, the airbag elastically supports an upper body of an occupantand elastically receives an impact force applied to a back surface ofthe seat back. After having deployed, the airbag has such a shape that adeployment amount, in a front-back direction, of the airbag near a backside of the seat back is greater than that near a front side of the seatback.

A fifth aspect of the present invention provides a vehicle seatincluding a seat back, a seat back frame disposed in the seat back, anairbag that is disposed in the seat back and that deploys in the seatback, and a reaction-force-receiving member that is disposed in the seatback and that controls a deployment direction of the airbag by receivinga reaction force generated when the airbag deploys. The airbag deploysin the seat back in such a way that, after having deployed, the airbagelastically supports an upper body of an occupant and elasticallyreceives an impact force applied to a back surface of the seat back.

The reaction-force-receiving member may be an elastic support memberthat is disposed across the seat back frame.

The airbag may be disposed between the elastic support member and theback surface of the seat back.

The airbag may be disposed between the elastic support member and a seatpad that is disposed in front of the elastic support member.

The airbag may be disposed between a lumbar support and the seat pad,the lumbar support being suspended in the seat back frame.

The reaction-force-receiving member may be a floating member that isfloatingly supported in the seat back frame via a tensile member fixedto the seat back frame.

The floating member may be floatingly supported by a plurality of thetensile members that cross each other between frames of the seat backframe, the frames facing each other, and the airbag may be supported bythe floating member at a position between the floating member andcrossing portions of the plurality of tensile members.

A sixth aspect of the present invention provides a vehicle seatincluding a seat back, a seat back frame disposed in the seat back, andan airbag that is disposed in the seat back and that deploys in the seatback. An entirety of the seat back frame has a substantially frame-likeshape extending along an outline of the seat back. The airbag isdisposed in the seat back frame. An inflator is attached to a floatingmember that is flexibly supported at a plurality of positions within theseat back frame. The inflator causes the airbag to deploy in the seatback in such a way that, after having deployed, the airbag elasticallysupports an upper body of an occupant and elastically receives an impactforce applied to a back surface of the seat back.

The floating body may be flexibly supported by a plurality of tensionsprings extending radially between the seat back frame and the floatingmember.

The floating member may be a flat member extending in a direction thatis substantially parallel to a direction in which the seat back extends.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view of a vehicle seat according to afirst example;

FIG. 2 is a partially cutaway rear perspective view of the vehicle seat;

FIG. 3 is a block diagram of a control circuit of an airbag;

FIG. 4 illustrates how the vehicle seat operates when a collisionoccurs;

FIG. 5A is a cross-sectional view of the vehicle seat taken along lineVA-VA of FIG. 1, and FIG. 5B is a cross-sectional view of the vehicleseat taken along line VB-VB of FIG. 4;

FIG. 6A is a cross-sectional view of a seat back, and FIG. 6Billustrates how the seat back operates;

FIG. 7A is a cross-sectional view of a seat back, and FIG. 7Billustrates how the seat back operates;

FIG. 8A is a longitudinal sectional view of a seat back according to asecond example, and FIG. 8B illustrates how the seat back operates;

FIG. 9A is a cross-sectional view of the seat back taken along lineIXA-IXA of FIG. 8A, and FIG. 9B is a cross-sectional view of FIG. 8Btaken along line IXB-IXB;

FIG. 10A is a longitudinal sectional view of a seat back, and FIG. 10Billustrates how the seat back operates;

FIG. 11 is a longitudinal sectional view of a vehicle seat according toa third example;

FIG. 12A is a cross-sectional view of the vehicle seat taken along lineXIIA-XIIA of FIG. 11, and FIG. 12B illustrates how the vehicle seatoperates;

FIG. 13A is a cross-sectional view of a seat back, and FIG. 13Billustrates how the seat back operates;

FIG. 14 is a longitudinal sectional view of a vehicle seat according toa fourth example of the present invention;

FIG. 15 is a partially cutaway rear perspective view of a vehicle seataccording to the fourth example;

FIG. 16 illustrates how the vehicle seat according to the fourth exampleoperates when a collision occurs;

FIG. 17 is a partially cutaway rear perspective view of a vehicle seataccording to a fifth example of the present invention;

FIG. 18 is a partially cutaway rear perspective view of a vehicle seataccording to a sixth example of the present invention;

FIG. 19 is cross-sectional view of the vehicle seat taken along lineXIX-XIX of FIG. 18;

FIG. 20 is a cross-sectional view of a seat back illustrating how thevehicle seat operates when a collision occurs;

FIG. 21 is a cross-sectional view of a vehicle seat according to amodification of the sixth example of the present invention, taken alonga line corresponding to line XIX-XIX of FIG. 18;

FIG. 22 is a cross-sectional view of the seat back according to themodification, illustrating how the vehicle seat operates when acollision occurs;

FIG. 23A is a partially cutaway rear perspective view of a lower part ofa vehicle seat according to a modification of the fifth example of thepresent invention, and FIG. 23B is a cross-sectional view of the lowerpart of the vehicle seat taken along line XXIIIB-XXIIIB of FIG. 23A;

FIG. 24A is a cross-sectional view illustrating an operation of a lumbarsupport when the lumbar support receives a load from the front side ofthe vehicle, and FIG. 24B is a partial enlarged view of a region XXIVBof FIG. 24A;

FIG. 25A is a cross-sectional view of a seat back illustrating anoperation of the vehicle seat according to the modification when acollision occurs, and FIG. 25B is a partial enlarged view of a regionXXVB of FIG. 25A;

FIG. 26 is a longitudinal sectional view of a vehicle seat according toa seventh example;

FIG. 27 is a partially cutaway rear perspective view of the vehicle seataccording to the seventh example; and

FIG. 28 illustrates how the vehicle seat according to the seventhexample operates when a collision occurs.

DETAILED DESCRIPTION

Hereinafter, vehicle seats according to examples of the presentinvention will be described with reference to the drawings.

First Example

Referring to FIGS. 1 to 5B, a vehicle seat according to a first exampleof the present invention will be described. FIG. 1 is a longitudinalsectional view of the vehicle seat according to the first example. FIG.2 is a partially cutaway rear perspective view of the vehicle seat. FIG.3 is a block diagram of a control circuit of an airbag. FIG. 4illustrates how the vehicle seat operates when a collision occurs. FIGS.5A and 5B, which illustrate how the vehicle seat operates, arerespectively a cross-sectional view of the vehicle seat taken along lineVA-VA of FIG. 1 and a cross-sectional view of the vehicle seat takenalong line VB-VB of FIG. 4. In each of the figures, an arrow F indicatesthe forward direction of the vehicle, and an arrow OUT indicates adirection outward in the vehicle-width direction.

As illustrated in FIG. 1, a front seat 10 and a rear seat 60, eachcorresponding to a vehicle seat, are disposed on a floor 1 in a vehicle.The front seat 10 includes a seat cushion 11, a seat back 20, and a headrest 45. The seat cushion 11 is supported on the floor 1 and supportsthe buttocks of an occupant Pf. The seat back 20 supports the upper bodyPb, including the abdomen and the chest, of the occupant Pf from behind.

As illustrated in FIGS. 1 and 2, the front seat 10 further includes aseat back frame 21, a plurality of elastic support members 27, a seatpad 28, and an airbag 30. The seat back frame 21 forms the skeleton ofthe seat back 20. The elastic support members 27 extend across the seatback frame 21. The seat pad 28 is disposed on the front sides of theelastic support members 27. The airbag 30 is disposed behind the elasticsupport members 27 in a deflated state. The entirety of the seat back 20is covered with a covering 41.

The seat back frame 21 includes an upper frame 22, a pair of side frames23, a pair of left and right side brackets 24, an upper cross member 25,and a lower cross member 26. The upper frame 22, which extends in thevehicle-width direction, and the pair of side frames 23, which extenddownward from both ends of the upper frame 22, form an angular-U-shapedor U-shaped pipe frame. The left and right side brackets 24 arerespectively fixed to side ends of the side frames 23. The upper crossmember 25, which is pipe-shaped, extends between upper end portions ofthe left and right side frames 23 in the vehicle-width direction. Thelower cross member 26 extends between lower end portions of the left andright side brackets 24. The seat back frame 21, which is made of thesecomponents, has a substantially rectangular frame-like shape.

The elastic support members 27, which are S-shaped springs or the likeeach made of a metal wire, extend between the side frames 23 and betweenthe side brackets 24. In the first example, the number of the elasticsupport members 27 is three. The seat pad 28, which is made of urethanefoam or the like, is disposed on the front sides of the elastic supportmembers 27. The airbag 30, which is folded in a flat rectangular shapein a deflated state, is disposed behind the elastic support members 27.

The covering 41 covers the entirety of the seat back 20, including theseat back frame 21, the seat pad 28, the airbag 30, and the like. Thecovering 41 is made of a stretchable cloth (fabric, knit, or nonwovencloth) or a stretchable leather (natural leather or synthetic leather).The covering 41 has a bag-like shape and includes a front portion 42,which covers the front side of the seat pad 28, and a back portion 43,which covers the airbag 30. The airbag 30 is deployably supported by thecovering 41 and the like through, for example, an engagement mechanism(not illustrated). The airbag 30 has a gas inlet (not illustrated),which is connected to an inflator 29 attached to one of the sidebrackets 24.

Bottom ends of the side brackets 24 of the seat back frame 21 of theseat back 20 are attached to rotary arms 16 of reclining mechanisms 15,which are disposed at rear ends of the seat cushion 11, by using bolts17. Thus, the seat back frame 21 is integrally connected with the rotaryarms 16 of the reclining mechanisms 15. Detailed description of thereclining mechanisms 15 will be omitted, because existing mechanisms canbe used as the reclining mechanisms 15 and the structure of thereclining mechanisms 15 is not directly related to the presentinvention.

As illustrated in FIGS. 1 and 2, a pair of left and right stay brackets47, each having a hollow cylindrical shape, are integrally formed withthe upper frame 22 of the seat back frame 21. The head rest 45 isattached to an upper end of the seat back 20 by inserting stays 46 ofthe head rest 45 into the stay brackets 47.

As illustrated FIG. 1 and FIG. 5A, which is a cross-sectional view takenalong line VA-VA of FIG. 1, the airbag 30, which is disposed between theelastic support member 27 and the back portion 43 of the covering 41,includes an airbag body 31 and a plurality of tethers 34. The airbagbody 31 is formed by sewing the periphery of a front covering 32 and theperiphery of a rear covering 33 together. The front covering 32 issubstantially rectangular and is disposed near the elastic supportmembers 27 so as to face the elastic support members 27. The rearcovering 33 is disposed near the back portion 43 of the covering 41 soas to face the front covering 32. The tethers 34 extend between centralparts, in the width direction, of the front covering 32 and the rearcovering 33. The tethers 34, each having a strip-like shape or atape-like shape, restrict the deployment amount of the airbag 30 in thefront-back direction.

The airbag 30 operates as follows when an inflation gas is supplied tothe airbag 30 from the inflator 29. The airbag 30 deploys between theelastic support members 27 and the back portion 43 of the covering 41.As illustrated in FIG. 4 and FIG. 5B, which is a cross-sectional viewtaken along line VB-VB of FIG. 4, the tethers 34 restrict a deploymentamount Lo in the front-back direction at the central part of the airbag30 in the width direction. An outer side portion 30 a of the airbag 30,which is located near a side portion of the seat back 20 facing a sidewall 2 of the vehicle, protrudes backward and in the vertical direction.Thus, the outer side portion 30 a deploys by a large deployment amountLa so as to provide a sufficient impact absorbing distance. An innerside portion 30 b of the airbag 30, which is located near an inner sideof the seat back 20, that is, near the center of the vehicle in thewidth direction, protrudes backward and in the vertical direction. Thus,the inner side portion 30 b deploys by a large deployment amount Lb inthe front-back direction. As the outer side portion 30 a and the innerside portion 30 b of the airbag 30 deploy, an outer region 43 a and aninner region 43 b of the back portion 43 of the covering 41 protrudeconsiderably.

In other words, after having deployed, the airbag 30 has such a shapethat the deployment amounts, in the front-back direction, of the outerside portion 30 a and the inner side portion 30 b, which are locatednear sides of the seat back 20, are greater than that of a portion ofthe airbag 30 near the center of the seat back 20. The airbag 30 has anorifice (not illustrated), through which the inflation gas is dischargedto the outside from the inside of the airbag 30.

The airbag 30 deploys while being held by the elastic support members 27and covered by the back portion 43 of the covering 41, which stretchesand protrudes. Therefore, the deployment of the airbag 30 is controlledso that the airbag 30 can stably deploy with a sufficient deploymentamount, and the airbag has a sufficient impact absorbing distance in thefront-back direction of the vehicle.

FIG. 3 illustrates a control circuit of a vehicle airbag. The controlcircuit includes a controller 50 that controls the deployment of theairbag 30. The controller 50 controls the operation of the inflator 29in accordance with information from a rear-end collision sensor 51,which predicts a rear-end collision of the vehicle and an impact load ofthe collision, and a program stored in a ROM 53.

The controller 50 includes a timer that measures the amount of timeelapsed from the time at which a rear-end collision is predicted tooccur. The rear-end collision sensor 51 includes a distance sensor, suchas a millimeter wave sensor. The rear-end collision sensor 51 predicts arear-end collision by measuring the distance between the vehicle andanother vehicle that might cause a collision and the relative speed ofthe other vehicle. Moreover, the rear-end collision sensor 51 predictsan impact load that will be applied to the vehicle if the predictedrear-end collision occurs.

When the rear-end collision sensor 51 of a vehicle, which has thevehicle seat described above, predicts a rear-end collision that willgenerate a predetermined impact load or more, the controller 50 outputsa signal to the inflator 29 and the inflator 29 discharges the inflationgas. Thus, the airbag 30 deploys from a deflated state, which isillustrated in FIGS. 1 and 5A, in a space between the elastic supportmember 27 and the back portion 43 of the covering 41 as illustrated inFIGS. 4 and 5B. Due to the deployment, the airbag 30 elasticallyreceives backward movement of the upper body Pb of an occupant in thefront seat Pf (as schematically indicated by an arrow Pf in FIG. 5B),which is caused by the rear-end collision, through the front portion 42of the covering 41, the seat pad 28, and the elastic support members 27;and therefore the airbag 30 restrains the backward movement.

An occupant Pr in the rear seat may move linearly forward (asschematically indicated by an arrow Pra) due to deformation of thevehicle body caused by an impact of a rear-end collision or due to arebound after moving backward and pressing a seat back during a rear endcollision. As a result, for example, a knee Pn of the occupant Pr maycontact the back surface of the seat back 20 of the front seat 10. Atthis time, the airbag 30, which has deployed between the elastic supportmembers 27 of the seat back 20 and the back portion 43 of the covering41, elastically receives the knee Pn through the covering 41, andrestrains the forward movement of the knee Pn. Thus, the upper body Pbof the occupant Pf in the front seat 10 is prevented from receiving animpact force from the knee Pn of the occupant Pr in the rear seat 60. Asa result, the occupant Pf is protected. Likewise, the deployed airbag 30elastically receives an impact force applied to the knee Pn of theoccupant Pr in the rear seat 60, who moves forward, due to contact ofthe knee Pn with the back surface of the seat back 20 and an impactforce applied to the upper body, including the chest, of the occupantPr. As a result, the occupant Pr is protected.

In particular, if the vehicle is involved in an offset rear-endcollision or the like and the vehicle yaws, it may happen that theoccupant Pf in the front seat 10 is moved diagonally backward toward theside wall 2, which is outward of the vehicle (as schematically indicatedby an arrow Pfb) and the occupant Pr in the rear seat is moveddiagonally forward toward the side wall 2 (as schematically indicated byan arrow Prb). In such a situation, the deployed airbag 30, inparticular, the outer side portion 30 a, which deploys by the largedeployment amount La, elastically receives the diagonal backwardmovement of the upper body Pb of the occupant Pf in the front seat 10through the front portion 42 of the covering 41, the seat pad 28, andthe elastic support members 27; and restrains the diagonal backwardmovement.

The outer side portion 30 a of the airbag 30, which has deployed so asto protrude backward in a space between the elastic support members 27of the seat back 20 and the outer region 43 a of the back portion 43 ofthe covering 41, elastically receives the knee Pn of the occupant Pr inthe rear seat 60 so as to restrain the knee Pn from moving forward andtoward the side wall 2. Thus, the upper body Pb of the occupant Pf inthe front seat 10 is protected from receiving an impact force from theknee Pn of the occupant Pr in the rear seat 60. Likewise, the outer sideportion 30 a of the airbag 30, which deploys by a sufficient deploymentamount so as to provide a sufficient impact absorbing distance,elastically receives an impact force applied to the knee Pn of theoccupant Pr in the rear seat 60 and an impact force applied to the upperbody of the occupant Pr, including the chest, and the occupant Pr isprevented from contacting the side wall 2 of the vehicle.

If the vehicle is involved in an offset rear-end collision or the likeand the vehicle yaws, it may happen that the occupant Pf in the frontseat 10 is moved diagonally backward toward the center in the vehiclewidth direction, which is inward of the vehicle (as schematicallyindicated by an arrow Pfc) and the occupant Pr in the rear seat is moveddiagonally forward toward the inside of the vehicle (as schematicallyindicated by an arrow Prc). In such a situation, the airbag 30, inparticular, the inner side portion 30 b, which deploys by the largedeployment amount Lb, elastically receives the diagonal backwardmovement of the upper body Pb of the occupant Pf in the front seat 10through the front portion 42 of the covering 41, the seat pad 28, andthe elastic support members 27; and restrains the diagonal backwardmovement.

The inner side portion 30 b of the airbag 30, which has deployed so asto protrude backward in a space between the elastic support members 27of the seat back 20 and the inner region 43 b of the back portion 43 ofthe covering 41, elastically receives the knee Pn of the occupant Pr inthe rear seat 60 so as to restrain the knee Pn from moving forwardtoward the center of the vehicle. Thus, the upper body Pb of theoccupant Pf in the front seat 10 is protected from receiving an impactforce from the knee Pn of the occupant Pr in the rear seat 60. Likewise,the inner side portion 30 b of the airbag 30 elastically receives animpact force applied to the knee Pn of the occupant Pr in the rear seat60 and an impact force applied to the upper body, including the chest,of the occupant Pr. As a result, the occupant Pr is protected.

With the structure described above, each of the outer side portion 30 aand the inner side portion 30 b of the airbag 30 deploys by a largeamount in the front-back direction. Accordingly, without using a complexstructure, the airbag 30 can directly protect the occupant Pf and canreduce an impact applied to the occupant Pf from behind the seat back 20during a collision.

In the example described above, the deployment amounts La and Lb of theouter side portion 30 a and the inner side portion 30 b in thefront-back direction are each greater than the deployment amount Lo of acentral portion of the airbag 30. Alternatively, only the deploymentamount La of the outer side portion 30 a may be greater than thedeployment amount Lo of the central portion of the airbag 30.

Referring to FIGS. 6A and 6B, this example will be described. FIG. 6A isa cross-sectional view of a seat back, and FIG. 6B illustrates how theseat back operates. Elements in FIGS. 6A and 6B corresponding to thosein FIGS. 5A and 5B will be denoted by the same numerals, and detaileddescriptions of such elements will be omitted.

As illustrated in FIG. 6A, the airbag 30, which is disposed between theelastic support members 27 and the back portion 43 of the covering 41,includes an airbag body 31 and a plurality of tethers 34. The airbagbody 31 is formed by sewing the periphery of a front covering 32 and theperiphery of a rear covering 33 together. The tethers 34 extend betweeninner parts and central parts, in the width direction, of the frontcovering 32 and the rear covering 33.

The airbag 30 operates as follows when an inflation gas is supplied tothe airbag 30 from the inflator 29. As illustrated in FIG. 6B, thetethers 34 restrict the deployment amount Lo in the front-backdirection. The outer side portion 30 a of the airbag 30, which islocated near a side portion of the seat back 20 facing the side wall 2of the vehicle, protrudes backward and in the vertical direction. Thus,the outer side portion 30 a deploys by a large deployment amount La inthe front-back direction. In other words, after having deployed, theairbag 30 has such a shape that the deployment amount, in the front-backdirection, of the outer side portion 30 a, which is located near a sideof the seat back 20, is greater than that of a portion of the airbag 30near the center of the seat back 20.

When a vehicle including the vehicle seat described above predicts arear-end collision, the airbag 30 deploys between the elastic supportmembers 27 and the back portion 43 of the covering 41 as illustrated inFIG. 6B. Due to the deployment, the airbag 30 elastically receives anrestrains backward movement of the upper body Pb of an occupant Pf inthe front seat 10, which is caused by the rear-end collision.

The deployed airbag 30 elastically receives the knee Pn of the occupantPr in the rear seat 60, and restrains forward movement of the knee Pn.Therefore, the occupant Pf in the front seat 10 is prevented fromreceiving an impact force from the knee Pn. As a result, the occupant Pfis protected. Likewise, the deployed airbag 30 elastically receivesimpact forces applied to the knee Pn and the upper body, such as thechest, of the occupant Pr in the rear seat 60, who moves forward. As aresult, the occupant Pr is protected.

If the vehicle is involved in an offset rear-end collision or the likeand the vehicle yaws, it may happen that the occupant Pf in the frontseat 10 is moved diagonally backward toward the side wall 2 of thevehicle, which is outward from the vehicle, and the occupant Pr in therear seat is moved diagonally forward toward the side wall 2 of thevehicle. In such a situation, the airbag 30, in particular, the outerside portion 30 a, which deploys by a large deployment amount,elastically receives the diagonal backward movement of the upper body Pbof the occupant Pf in the front seat 10 through the seat pad 28 and theelastic support members 27. As a result, the backward movement of theoccupant Pf is restrained.

Moreover, the outer side portion 30 a of the airbag 30, which hasdeployed so as to protrude backward, elastically receives the knee Pn ofthe occupant Pr in the rear seat 60 and restrains movement of the kneePn diagonally forward toward the side wall 2 of the vehicle. As aresult, the occupant Pf in the front seat 10 is protected. Likewise, theouter side portion 30 a of the deployed airbag 30 elastically receivesthe knee Pn, the chest, and the like of the occupant Pr in the rear seat60, who moves forward, and prevents the knee Pr and the like fromcontacting the side wall 2 of the vehicle. As a result, the occupant Pris protected.

Further alternatively, only the deployment amount Lb of the inner sideportion 30 b may be greater than the deployment amount Lo of the centralportion of the airbag 30. Referring to FIGS. 7A and 7B, this examplewill be described. FIG. 7A is a cross-sectional view of a seat back, andFIG. 7B illustrates how the seat back operates. Elements in FIGS. 7A and7B corresponding to those in FIGS. 6A and 6B will be denoted by the samenumerals, and detailed descriptions of such elements will be omitted.

As illustrated in FIG. 7A, the airbag 30, which is disposed between theelastic support members 27 and the back portion 43 of the covering 41,includes an airbag body 31 and a plurality of tethers 34. The airbagbody 31 is formed by sewing the periphery of a front covering 32 and theperiphery of a rear covering 33 together. The tethers 34 extend betweenouter parts and central parts, in the width direction, of the frontcovering 32 and the rear covering 33.

The airbag 30 operates as follows when an inflation gas is supplied tothe airbag 30 from the inflator 29. As illustrated in FIG. 7B, thetethers 34 restrict the deployment amount Lo in the front-backdirection. The inner side portion 30 b of the airbag 30, which islocated near an inner side of the seat back 20, protrudes backward andin the vertical direction, and the inner side portion 30 b deploys by alarge deployment amount Lb in the front-back direction. In other words,after having deployed, the airbag 30 has such a shape that thedeployment amount, in the front-back direction, of the inner sideportion 30 b, which is located near an inner side of the seat back 20,is greater than that of a portion of the airbag 30 near the center ofthe seat back 20.

When a vehicle including the vehicle seat described above predicts arear-end collision, the airbag 30 deploys between the elastic supportmembers 27 and the back portion 43 of the covering 41 as illustrated inFIG. 7B. The deployed airbag 30 elastically receives and restrainsbackward movement of the upper body Pb of an occupant Pf in the frontseat 10, which is caused by the rear-end collision.

The deployed airbag 30 elastically receives the knee Pn of the occupantPr in the rear seat 60, and restrains forward movement of the knee Pn.Therefore, the occupant Pf in the front seat 10 is prevented fromreceiving an impact force from the knee Pn. As a result, the occupant Pfis protected. Likewise, the deployed airbag 30 elastically receivesimpact forces applied to the knee Pn and the upper body, such as thechest, of the occupant Pr in the rear seat 60, who moves forward. As aresult, the occupant Pr is protected.

If the vehicle is involved in an offset rear-end collision or the likeand the vehicle yaws, it may happen that the occupant Pf in the frontseat 10 is moved diagonally backward toward the center of the vehicle,and the occupant Pr in the rear seat is moved diagonally forward towardthe center of the vehicle. In such a situation, the airbag 30, inparticular, the inner side portion 30 b that deploys by a largedeployment amount, elastically receives the diagonal backward movementof the upper body Pb of the occupant Pf in the front seat 10 through theseat pad 28 and the elastic support members 27; and restrains thebackward movement.

The inner side portion 30 b of the airbag 30, which has deployed so asto protrude backward, elastically receives the knee Pn of the occupantPr in the rear seat 60 and restrains movement of the knee Pn. As aresult, the occupant Pf in the front seat 10 is prevented from receivingan impact force from the knee Pn, and the occupant Pf is protected.Likewise, the inner side portion 30 b of the deployed airbag 30elastically receives the knee Pn and the upper body, such as the chest,of the occupant Pr in the rear seat 60, who moves forwards. As a result,the occupant Pr is protected.

By forming the airbag 30 in such a way that one of the outer sideportion 30 a and the inner side portion 30 b deploys backward by a largeamount, the size and the deployment amount of the airbag 30 can bereduced and the output power of the inflator 29 can be reduced, ascompared with the case where both the outer side portion 30 a and theinner side portion 30 b of the airbag 30 are deployed by large amounts.

Second Example

Referring to FIGS. 8A to 9B, a vehicle seat according to a secondexample of the present invention will be described. FIG. 8A is alongitudinal sectional view of a seat back according to a secondexample, and FIG. 8B illustrates how the seat back operates. FIG. 9A isa cross-sectional view of the seat back taken along line IXA-IXA of FIG.8A, and FIG. 9B is a cross-sectional view of FIG. 8B taken along lineIXB-IXB. Elements in FIGS. 8A to 9B corresponding to those in FIGS. 1 to7B will be denoted by the same numerals, and detailed descriptions ofsuch elements will be omitted.

As in the first example, a seat back 20 of a front seat 10 includes aseat back frame 21, a plurality of elastic support members 27, a seatpad 28, and an airbag 30. The elastic support members 27 extend acrossthe seat back frame 21. The seat pad 28 is disposed on the front sidesof the elastic support members 27. The airbag 30 is disposed behind theelastic support members 27 in a deflated state. The entirety of the seatback 20 is covered with a covering 41, which is stretchable and has abag-like shape.

As illustrated in FIGS. 8A and 8B, the airbag 30 includes an airbag body31 and a plurality of tethers 34. The airbag body 31 is formed by sewingthe periphery of a front covering 32 and the periphery of a rearcovering 33 together. The front covering 32 is substantially rectangularand is disposed near the elastic support members 27. The rear covering33 is disposed near a back portion 43 of the covering 41. As illustratedin FIGS. 9A and 9B, the tethers 34 are disposed with equal distancestherebetween in the width direction of the seat so as to extend betweenlower parts of the front covering 32 and the rear covering 33. Thetethers 34, each having a strip-like shape or a tape-like shape,restrict the deployment amount of the airbag 30 in the front-backdirection.

The airbag 30 operates as follows when an inflation gas is supplied tothe airbag 30 from the inflator 29. The airbag 30 deploys between theelastic support members 27 and the back portion 43 of the covering 41.As illustrated in FIGS. 8B and 9B, the tethers 34 restrict a deploymentamount Ld of a lower portion 30 d, which corresponds to a lower regionof the seat back and to the height of the knee Pn of the occupant Pr inthe rear seat 60. An upper portion 30 h, which corresponds to an upperregion of the seat back 20 and to the height of the chest of theoccupant Pr in the rear seat 60, deploys so as to protrude backward by alarge amount. Thus, the upper portion 30 h deploys by a large deploymentamount Lh in the front-back direction. As the upper portion 30 h of theairbag 30 deploys, the upper region of the back portion 43 of thecovering 41 protrudes by a large amount or may become torn. In otherwords, after having deployed, the airbag 30 has such a shape that thedeployment amount of the airbag 30, in the front-back direction, near anupper part of the seat back 20 is greater than that near a lower part ofthe seat back 20.

As illustrated in FIG. 9B, each of the tethers 34 locally restricts thedeployment amount of the lower portion 30 d of the airbag 30, so that anundulating surface 30 e is formed on the rear covering 33. Theundulating surface 30 e on the back side of the airbag 30 restrictsmovement of the knee Pn of the occupant Pr in the rear seat 60, whichserves as an impact applying member that applies an impact force to theback side of the seat back 20.

The airbag 30 deploys while being held by the elastic support members 27and covered by the back portion 43 of the covering 41, which stretchesand protrudes. Therefore, the deployment of the airbag 30 is controlledso that the airbag 30 can stably deploy with a sufficient deploymentamount, and the airbag 30 has a sufficient impact absorbing distance inthe front-back direction of the vehicle.

When a vehicle including the vehicle seat described above predicts arear-end collision, the airbag 30 deploys between the elastic supportmembers 27 and the back portion 43 of the covering 41 as illustrated inFIG. 8B. The deployed airbag 30 elastically receives and restrainsbackward movement of the upper body Pb of an occupant Pf in the frontseat 10, which is caused by the rear-end collision, through the frontportion 42 of the covering 41, the seat pad 28, and the elastic supportmembers 27.

The occupant Pr in the rear seat 60 is moved forward due to the impactof the rear-end collision. At this time, the knee Pn is fitted onto andelastically received by the undulating surface 30 e of the lower portion30 d of the deployed airbag 30, so that forward movement of the knee Pnis restrained. Therefore, the upper body Pb of the occupant Pf in thefront seat 10 is prevented from receiving an impact force from the kneePn of the occupant Pr in the rear seat 60. As a result, the occupant Pfis protected.

Likewise, the knee Pn of the occupant Pr, who moves forward, iselastically received and protected by the lower portion 30 d of thedeployed airbag 30. At this time, the knee Pn is fitted onto theundulating surface 30 e of the lower portion 30 d of the airbag 30 asillustrated by an imaginary line in FIG. 8B. Therefore, relativemovement between the lower portion 30 d of the airbag 30 and the knee Pnis restrained, and the knee Pn is elastically received by the airbag 30.

The upper portion 30 h of the airbag 30, which has considerably deployedand protruded as indicated by an imaginary line in FIG. 8B, elasticallyreceives and protects the upper body, such as the chest, of the occupantPr in the rear seat 60, who moves forward.

In the example described above, the deployment amount, in the front-backdirection, of the upper portion 30 h of the airbag 30, which is near anupper part of the seat back 20, is greater than that of the lowerportion 30 d, which is near a lower part of the seat back 20.Alternatively, the deployment amount of the lower portion 30 d in thefront-back direction may be greater than that of the upper portion 30 f.

Referring to FIGS. 10A and 10B, this example will be described. FIG. 10Ais a cross-sectional view of a seat back, and FIG. 10B illustrates howthe seat back operates. Elements in FIGS. 10A and 10B corresponding tothose in FIGS. 8A and 8B will be denoted by the same numerals, anddetailed descriptions of such elements will be omitted.

A seat back 20 of a front seat 10 includes a seat back frame 21, aplurality of elastic support members 27, a seat pad 28, and an airbag30. The elastic support members 27 extend across the seat back frame 21.The seat pad 28 is disposed on the front sides of the elastic supportmembers 27. The airbag 30 is disposed behind the elastic support members27. The entirety of the seat back 20 is covered with a covering 41,which is stretchable and has a bag-like shape.

As illustrated in FIGS. 10A and 10B, the airbag 30, which is disposedbetween the elastic support members 27 and a back portion 43 of thecovering 41, includes an airbag body 31 and a plurality of tethers 34.The airbag body 31 is formed by sewing the periphery of a front covering32 and the periphery of a rear covering 33 together. The tethers 34, forrestricting the deployment amount in the front-back direction, extendbetween upper parts of the front covering 32 and the rear covering 33 inthe width direction.

The airbag 30 operates as follows when an inflation gas is supplied tothe airbag 30 from the inflator 29. The airbag 30 deploys between theelastic support members 27 and the back portion 43 of the covering 41.As illustrated in FIG. 10B, the tethers 34 restrict the deploymentamount Lh of an upper portion 30 h, which is near an upper region of theseat back 20. A lower portion 30 d, which is located near a lower regionof the seat back 20 and corresponds to the height of the knee Pn of theoccupant Pr in the rear seat 60, deploys so as to protrude backward, andthe lower portion 30 d deploys by a large deployment amount Ld in thefront-back direction.

When a vehicle including the vehicle seat described above predicts arear-end collision, the airbag 30 deploys between the elastic supportmembers 27 and the back portion 43 of the covering 41 as illustrated inFIG. 10B. The deployed airbag 30 elastically receives and restrainsbackward movement of the upper body Pb of an occupant Pf in the frontseat 10, which is caused by the rear-end collision, through the frontportion 42 of the covering 41, the seat pad 28, and the elastic supportmembers 27.

The knee Pn of the occupant Pr in the rear seat 60 is elasticallyreceived and restrained by the lower portion 30 d of the deployed airbag30, which has deployed by a large amount, so that forward movement ofthe knee Pn is restrained. Therefore, the upper body Pb of the occupantPf in the front seat 10 is protected from receiving an impact force fromthe knee Pn. As a result, the occupant Pf in the front seat isprotected. The lower portion 30 d of the deployed airbag 30 elasticallyreceives and protects the knee Pn of the occupant Pr in the rear seat60, who moves forward.

With the structures described above, the deployment amount of the lowerportion 30 d of the airbag 30 in the front-back direction is greaterthan that of the upper portion 30 h, or the deployment amount of theupper portion 30 h is greater than that of the lower portion 30 d.Accordingly, without using a complex structure, the airbag 30 candirectly protect the occupant Pf and can reduce an impact applied to theoccupant Pf from behind the seat back 20 during a collision. Also inthis case, an undulating surface that restrains and supports the knee Pnof the occupant Pf in the rear seat 60 may be formed on the back side ofthe airbag 30 as in the case described above.

Third Example

Referring to FIGS. 11 to 12B, a vehicle seat according to a thirdexample of the present invention will be described. FIG. 11 is alongitudinal sectional view of the vehicle seat. FIG. 12A is across-sectional view of the vehicle seat taken along line XIIA-XIIA ofFIG. 11, and FIG. 12B illustrates how the vehicle seat operates.Elements in FIGS. 11 to 12B corresponding to those in FIGS. 1 to 7B willbe denoted by the same numerals, and detailed descriptions of suchelements will be omitted.

A seat back 20 of a front seat 10 includes a seat back frame 21, aplurality of elastic support members 27, a seat pad 28, and an airbag30. The elastic support members 27 extend across the seat back frame 21.The seat pad 28 is disposed on the front sides of the elastic supportmembers 27. The airbag 30 is disposed behind the elastic support members27 in a deflated state. The entirety of the seat back 20 is covered witha covering 41, which is stretchable and has a bag-like shape.

As illustrated in FIGS. 12A and 12B, the airbag 30, which is disposedbetween the elastic support members 27 and the back portion 43 of thecovering 41, includes an airbag body 31. The airbag body 31 is formed bysewing the periphery of a front covering 32 and the periphery of a rearcovering 33 together. The front covering 32 is disposed near the elasticsupport members 27 so as face the elastic support members 27. The rearcovering 33 is substantially rectangular and is disposed near the backportion 43 of the covering 41.

FIG. 12B illustrates the airbag 30 in a deployed state. The airbag 30deploys in such a way that the front covering 32 of the airbag body 31deploys by a deployment amount Lf in the front-back direction, which iscomparatively large, and the rear covering 33 deploys by a deploymentamount Lr in the front-back direction, which is considerably smallerthan the deployment amount Lf of the front covering 32. In other words,the deployment amount of the airbag 30, in the front-back direction,near the elastic support members 27, which is near the front side of theseat back 20, is greater than that near the back portion 43, which isnear the back side of the seat back 20.

When the airbag 30 having the structure described above rapidly deploysbetween the elastic support members 27 and the back portion 43 of thecovering 41, as compared with a case where an airbag that deploys by thesame amounts toward the front side and the back side, a larger pressingforce is applied to a portion of the airbag 30 near the elastic supportmembers 27 and a comparatively small pressing force is applied to aportion of the airbag 30 near the back portion 43.

When a vehicle including the vehicle seat described above predicts arear-end collision, the airbag 30 deploys between the elastic supportmembers 27 and the back portion 43 of the covering 41 as illustrated inFIG. 12B. As the airbag 30 deploys, a portion of the airbag 30 near theelastic support members 27 is pressed forward with a comparative largepressing force, so that the occupant Pf in the front seat 10 is receivedcomparatively securely and backward movement of the occupant Pf isrestrained.

The knee Pn of the occupant Pr in the rear seat 60 is comparativelygently received by the deployed airbag 30, so that forward movement ofthe knee Pn is restrained. Therefore, the upper body Pb of the occupantPf in the front seat 10 is prevented from receiving an impact force fromthe knee Pn of the occupant Pr in the rear seat 60. Likewise, the kneePn of the occupant Pr, who moves forward, is elastically received andprotected by the lower portion 30 d of the deployed airbag 30.

The airbag 30, after having deployed, may have such a shape that thedeployment amount of the airbag 30 in the front-back direction near theback side of the seat back 20 may be greater than that near the frontside of the seat back 20. Referring to FIGS. 13A and 13B, this examplewill be described. FIGS. 13A and 13B are cross-sectional viewsrespectively corresponding to FIGS. 12A and 12B. Elements in FIGS. 13Aand 13B corresponding to those in FIGS. 12A and 12B will be denoted bythe same numerals, and detailed descriptions of such elements will beomitted.

As illustrated in FIGS. 13A and 13B, the airbag 30, which is disposed inthe seat back 20 between the elastic support members 27 and the backportion 43 of the covering 41, includes an airbag body 31. The airbagbody 31 is formed by sewing the periphery of a front covering 32 and theperiphery of a rear covering 33 together. The front covering 32 isrectangular and is disposed near the elastic support members 27 so as toface the elastic support members 27. The rear covering 33 is disposednear the back portion 43 of the covering 41 so as to face the frontcovering 32.

FIG. 13B illustrates the airbag 30 in a deployed state. The airbag 30deploys in such a way that the front covering 32 of the airbag body 31deploys by a deployment amount Lf in the front-back direction, which iscomparatively small, and the rear covering 33 deploys by a deploymentamount Lr in the front-back direction, which is considerably greaterthan the deployment amount Lf of the front covering 32. In other words,the deployment amount of the airbag 30, in the front-back direction,near the back portion 43, which is near the back side of the seat back20, is greater than that near the elastic support members 27, which isand the front side of the seat back 20.

When the airbag 30 having the structure described above rapidly deploysbetween the elastic support members 27 and the back portion 43 of thecovering 41, as compared with a case where an airbag that deploys by thesame amounts toward the front side and the back side, a larger pressingforce is applied to a portion of the airbag 30 near the back portion 43and a comparatively small pressing force is applied to a portion of theairbag 30 near the elastic support members 27.

When a vehicle including the vehicle seat described above predicts arear-end collision, the airbag 30 deploys between the elastic supportmembers 27 and the back portion 43 of the covering 41 as illustrated inFIG. 13B. As the airbag 30 deploys, a portion of the airbag 30 near theelastic support members 27 is pressed forward with a comparative smallpressing force, so that the occupant Pf in the front seat 10 is receivedcomparatively gently and backward movement of the occupant Pf isrestrained.

The knee Pn of the occupant Pr in the rear seat 60 is comparativelysecurely received by the deployed airbag 30 when the occupant Pr ismoved forward due to an impact of collision, so that forward movement ofthe knee Pn is restrained. Therefore, the upper body Pb of the occupantPf in the front seat 10 is prevented from receiving an impact force fromthe knee Pn of the occupant Pr in the rear seat 60. As a result, theoccupant Pf is protected. Likewise, the knee Pn of the occupant Pr, whomoves forward, is elastically received and protected by the lowerportion 30 d of the deployed airbag 30.

Thus, according to the example described above, the deployment amountsof the airbag, which is disposed in the seat back, toward the front sideand toward the back side are made to differ from each other by using asimple structure. Therefore, backward movement of an occupant due to acollision is elastically received, and the occupant can be protectedfrom a rear impact. As a result, during a collision, the airbag candirectly protect the occupant and can reduce an impact applied to theoccupant from behind the seat back.

In the examples described above, the deployment of the airbag 30 iscontrolled on the basis of prediction of a collision by a collisionpredictor. Alternatively, the deployment of the airbag 30 may becontrolled on the basis of detection of a collision by a collisiondetector that detects a collision.

Fourth Example

Referring to FIGS. 14 to 16, a vehicle seat according to a fourthexample of the present invention will be described. FIG. 14 is alongitudinal sectional view of the vehicle seat according to the fourthexample. FIG. 15 is a partially cutaway rear perspective view of thevehicle seat according to the fourth example. FIG. 16 illustrates howthe vehicle seat according to the fourth example operates when acollision occurs. Elements in the fourth example corresponding to thoseof the first example be denoted by the same numerals, and detaileddescriptions of such elements will be omitted.

The forth example differs from the first example in the structure of theairbag.

An airbag 30 according to the fourth example does not include thetethers 34 extending in the airbag 30. The airbag 30 is attached to theback portion 43 of the covering 41 in a state in which the airbag 30 isfolded into a flat rectangular shape behind the elastic support members27. The airbag 30 is disposed between the elastic support members 27 andthe back portion 43 of the covering 41. Thus, as described below, in thefourth example, reaction-force-receiving members, which determine thedeployment direction of the airbag 30 by receiving a reaction force whenthe airbag 30 deploys, are the elastic support members 27 extendingbetween the side brackets 24.

Accordingly, as illustrated in FIGS. 14 and 15, the airbag 30, which hasa substantially rectangular flat shape in a deflated state, is disposedin a space in the seat back 20 between the elastic support members 27and the back portion 43 of the covering 41. When the airbag 30 deploys,the seat back 20 covers the front side of the airbag 30 with the elasticsupport members 27, the seat pad 28, and the covering 41, and covers theback side of the airbag 30 with the covering 41, which is made of aflexible material.

The operation of a vehicle seat 65 having the structure describe abovewill be described below by using a rear-end collision of a vehicle as anexample.

When a vehicle including the vehicle seat 65 according to the fourthexample collides with another vehicle coming from behind and therear-end collision sensor 51 predicts a rear-end collision having apredetermined impact load or more, the controller 50 outputs a drivesignal to the inflator 29, and the inflator 29 discharges an inflationgas. Thus, as illustrated in FIG. 16, the airbag 30 deploysinstantaneously in a region between the elastic support members 27 andthe back side of the seat back 20.

As the airbag 30 deploys, the elastic support members 27, the seat pad28, the covering 41, and the like, which are made of flexible materialsand which covers the front side of the airbag 30, become deformedslightly in the forward direction of the vehicle as illustrated in FIG.16. The back portion 43 of the covering 41, which is made of a flexiblematerial and which covers the back side of the airbag 30, protrudes andbecomes deformed considerably in the backward direction of the vehicle.

The vehicle seat 65 according to the fourth example is characterized inthat, due to deformation of the flexible members or flexible materialsin front of and behind the airbag 30, the airbag 30 can deploy by asufficiently large deployment amount E in the front-back direction, andthe seat back 20 provides a large impact absorbing distance in thefront-back direction of the vehicle.

In other words, as illustrated in FIG. 16, the covering 41 on the frontside of the seat back 20, the seat pad 28, the elastic support members27, and the deployed airbag 30 elastically receive backward movement ofthe upper body of the occupant Pf in the vehicle seat 65 (front seat)due to an impact of the rear-end collision. Therefore, the upper body ofthe occupant Pf in the vehicle seat 65 (front seat) is protected from animpact that occurs when the upper body is pressed against the seat back20 due to the rear-end collision.

An occupant Pr in the rear seat is pressed against the rear seat 60 dueto an impact of the rear-end collision and then moved forward due to arebound. A knee of the occupant Pr in the rear seat, who moves forwarddue to the rebound, is elastically received by the covering 41 on theback side of the seat back 20 and the deployed airbag 30. Therefore, theupper body of the occupant Pf in the vehicle seat 65 (front seat) isprotected from an impact of the knee of the rear seat occupant Pr.

At this time, the airbag 30 deploys stably in the seat back 20, which islocated directly behind the upper body of the occupant Pf in the vehicleseat 65, while being restrained to a certain degree due to the innershape of the seat back 20. Therefore, the airbag 30 can reliably receivebackward movement of the upper body of the occupant Pf, absorb an impactdue to forward movement of the knee of the occupant Pr in the rear seat.As a result, the occupant Pf can be appropriately protected.

Protection of the occupant Pf is performed by using the dispositions ofthe airbag 30, which deploys in the seat back 20, and flexible materials(that is, the covering 41, the seat pad 28, the elastic support members27, and the like) in front of and behind the airbag 30. As a result, thestructure is considerably simplified.

Moreover, because the elastic support members 27 serve asreaction-force-receiving members that cause the airbag 30 to deploy in adirection backward from the seat back, the airbag 30 can effectivelyabsorb an impact due to forward movement of the occupant Pr, which theairbag 30 receives from behind the seat back.

In the fourth example, how the vehicle seat 65 functions during acollision is described above by using an example of a rear-end collisionof the vehicle. However, the collision is not limited to a rear-endcollision. For example, also in a frontal collision, although the orderis opposite to that of a rear-end collision, as the airbag 30 deploys,the vehicle seat 65 can first elastically receive an impact due toforward movement of the knee of the occupant Pr in the rear seat, andthen can elastically receive backward movement of the upper body of theoccupant in the vehicle seat 65.

Fifth Example

Referring to FIG. 17, a vehicle seat according to a fifth example of thepresent invention will be described. In the fourth example, the airbag30 is made to deploy in the backward direction from the seat back byusing the elastic support members 27 as reaction-force-receiving membersand disposing the airbag 30 behind the elastic support members 27. Asdescribed below, the fifth example has a structure in which thereaction-force-receiving members are partly changed and the deploymentdirection of the airbag 30 is changed. Elements in the fifth examplecorresponding to those of the fourth example be denoted by the samenumerals, and detailed descriptions of such elements will be omitted.

FIG. 17 is a partially cutaway rear perspective view of a vehicle seat70 according to the fifth example. As illustrated in FIG. 17, in thevehicle seat 70 according to the fifth example 70, the overall structureof the seat back 20, excluding the structure of reaction-force-receivingmembers, is the same as that of the fourth example. Therefore, detaileddescription of the overall structure will be omitted.

In the fifth example, elastic support members 72 are two S-springs madeof metal wires. The elastic support members 72 extend between sidebrackets 24 in an upper part of a substantially rectangular region Rsurrounded by an upper cross member 25, side frames 23, the sidebrackets 24, and a lower cross member 26.

In a lower part of the substantially rectangular region R, a flatplate-like lumbar support 74 is supported between the side brackets 24by tension springs 76. The tension springs 76 are hooked to U-shapedhooks 74 b, which are disposed on side portions 74 a of the lumbarsupport 74 and to U-shaped hooks (not illustrated), which are disposedon the side brackets 24.

The lumbar support 74, which is supported by the tension springs 76,presses the spine of the occupant Pf forward through the seat pad 28, sothat the occupant Pf (driver) can drive the vehicle in a naturalposition. In other words, the lumbar support 74 helps the spine of theoccupant Pf to maintain an inverted-S-shaped gentle curve and reducesstrain on the back of the driver during a long-hour driving.

An airbag 78 is folded into a shape corresponding to that of thesubstantially rectangular region R in a rear view and is disposed in thesubstantially rectangular region R. In the fifth example, the airbag 78is attached to the seat pad 28 at a position in front of the elasticsupport members 72 and the lumbar support 74.

Accordingly, in the fifth example, the elastic support members 72 andthe lumbar support 74 correspond to the reaction-force-receivingmembers, and the airbag 78 is disposed between thereaction-force-receiving members and the seat pad 28.

With this structure, when the airbag 78 deploys in the seat back 20 dueto a collision (such as a rear-end collision), the airbag 78 activelydeploys forward by receiving a large reaction force from the elasticsupport members 72 and the lumbar support 74, which are disposed behindthe airbag 78. Therefore, the airbag 78 can more effectively receive andabsorb an impact that might press the upper body of an occupant Pf inthe front seat against the seat back 20.

Sixth Example

Referring to FIGS. 18 to 20, a vehicle seat according to a sixth exampleof the present invention will be described. FIG. 18 is a partiallycutaway rear perspective view of a vehicle seat according to the sixthexample of the present invention. FIG. 19 is cross-sectional view of thevehicle seat taken along line XIX-XIX of FIG. 18. FIG. 20 is across-sectional view of a seat back illustrating how the vehicle seatoperates when a collision occurs. The sixth example differs from thefourth and fifth examples in that not only the elastic support members27 but also tensile members 82 a and 82 b and a floating member 84(described below) are used as reaction-force-receiving members.

In the sixth example, as illustrated in FIGS. 18 and 19, the tensilemembers 82 a and 82 b, each of which is made from a rope of a naturalfiber or a chemical fiber, are disposed between side brackets 24 a and24 b behind the elastic support members 27. The tensile members 82 a and82 b floatingly support the floating member 84 in a substantiallyrectangular region R surrounded by the upper cross member 25, the sideframes 23, the side brackets 24 a and 24 b, and the lower cross member26 in such a way that the tensile members 82 a and 82 b extend with apredetermined slack in a normal state.

The floating member 84 is a cloth or a net that has a rectangular shapewith diagonally cut corners in a plan view. The back side of thefloating member 84 is fixed to the back side of the seat back 20, andthe airbag 30 is supported by the front side of the floating member 84.How the tensile members 82 a and 82 b floatingly support the floatingmember 84 will be described below.

First ends of two tensile members 82 a are fixed to the inside of theside bracket 24 a, which is on an inner side in the vehicle-widthdirection, so as to be separated from each other by a predetermineddistance in the height direction. The tensile members 82 a extendthrough a space in front of the airbag 30 toward the side bracket 24 b,which is on an outer side in the vehicle-width direction. The tensilemembers 82 a are bent toward the back side of the airbag 30 at side endsof the airbag 30. Second ends of the tensile members 82 a are fixed tocorners 84 a on an outer side of the floating member 84 in thevehicle-width direction.

First ends of two tensile members 82 b, which correspond to the twotensile members 82 a, are fixed to the inside of the side bracket 24 b,which is on the outer side in the vehicle-width direction. The tensilemembers 82 b extend, while crossing the tensile members 82 a, through aspace in front of the airbag 30 toward the side bracket 24 a, which ison the inner side in the vehicle-width direction. The tensile members 82b are bent toward the back side of the airbag 30 at side ends of theairbag 30. Second ends of the tensile members 82 b are fixed to corners84 b on an inner side of the floating member 84 in the vehicle-widthdirection.

As illustrated in FIG. 19, a one-way clutch 86, which has an annularshape and through which the tensile members 82 a and 82 b extend, isdisposed at crossing portions of the tensile members 82 a and thetensile members 82 b. The one-way clutch 86, including a ratchet (notillustrated), freely allows the tensile members 82 a and 82 b to passtherethrough in a direction from the side brackets 24 a and 24 b towardthe floating member 84, but does not allow the tensile members 82 a and82 b to pass therethrough in the opposite direction (that is, in adirection from the floating member 84 toward the side brackets 24 a and24 b).

Accordingly, the floating member 84 is floatingly supported by the sidebrackets 24 a and 24 b through the tensile members 82 a and 82 b, whichextend between the side brackets 24 a and 24 b with a predeterminedslack in a normal state, and the airbag 30 is supported in thesubstantially rectangular region R in a state in which the airbag 30 issurrounded by the tensile members 82 a and 82 b and the floating member84.

With this structure, because the airbag 30 is located between theelastic support members 27 and the back side of the seat back 20, whenthe airbag 30 deploys as the inflator 29 is activated due to acollision, the elastic support members 27 serve asreaction-force-receiving members as illustrated in FIG. 20, and theairbag 30 deploys in the backward direction of the seat back 20.

As the volume of the airbag 30 increases due to the deployment, theslack of the tensile member 82 a and 82 b are removed, and the tensilemembers 82 a and 82 b and the floating member 84 become stretched. Then,the airbag 30 receives reaction forces from the tensile member 82 a and82 b and the floating member 84, which have become stretched. Therefore,the deployment of the airbag 30 in a direction toward the back side ofthe seat back 20 is restrained, and the position of the deployed airbag30 is controlled to be located between the side brackets 24 a and 24 b.

In the sixth example, not only the elastic support members 27 but alsothe tensile members 82 a and 82 b and the floating member 84 are used asreaction-force-receiving members. Referring to FIGS. 21 and 22, amodification of the sixth example, in which the floating member 84 isnot used, will be described below.

FIG. 21 is a cross-sectional view of a vehicle seat 80 according to amodification of the sixth example of the present invention, taken alonga line corresponding to line XIX-XIX of FIG. 18. FIG. 22 is across-sectional view of a seat back of the vehicle seat 80 according tothe modification, illustrating how the vehicle seat 80 operates when acollision occurs. As illustrated in FIG. 21, in the vehicle seat 80according to the modification, the overall structure of the seat back20, excluding the structure of reaction-force-receiving members and thestructure of the airbag, is the same as that of the sixth example.Therefore, detailed description of the overall structure will beomitted.

In the present modification, as illustrated in FIG. 21, tensile members90 a and 90 b are disposed between the side brackets 24 a and 24 bbehind the elastic support members 27. The tensile members 90 a and 90 bdirectly and floatingly support an airbag 92 in a substantiallyrectangular region R (see FIG. 17) surrounded by the upper cross member25, the side frames 23, the side brackets 24 a and 24 b, and the lowercress member 26 in such a way that the tensile members 90 a and 90 bextend with a predetermined slack in a normal state. How the tensilemembers 90 a and 90 b floatingly support the airbag 92 will be describedbelow.

The airbag 92 is folded into a shape corresponding to that of thesubstantially rectangular region R and is disposed in the region R. Inthe present modification, the airbag 92 is floatingly supported by thetensile members 90 a and 90 b between the side brackets 24 a and 24 b.The back side of the airbag 92, which is in a floatingly supportedstate, may be attached to the back side of the seat back 20.

As in the sixth example, first ends of two tensile members 90 a arefixed to the inside of the side bracket 24 a, which is on an inner sidein the vehicle-width direction, so as to be separated from each other bya predetermined distance in the height direction. As illustrated in FIG.21, the tensile members 90 a extend through a space in front of theairbag 92 toward the side bracket 24 b, which is on an outer side in thevehicle-width direction. The tensile members 90 a are inserted into theairbag 92 from the front side of the airbag 92 at substantially themidpoint between the side brackets 24 a and 24 b. Second ends of thetensile members 90 a are fixed to side portions 92 a of the airbag 92 onthe outer side in the vehicle-width direction. In this case, the tensilemembers 90 a are inserted into the airbag 92 through, for example,orifices (not illustrated) through which a gas is discharged from theinside to the outside of the airbag 92.

First ends of two tensile members 90 b, which correspond to the twotensile members 90 a, are fixed to the inside of the side bracket 24 b,which is on an outer side in the vehicle-width direction. The tensilemembers 90 b extend through a space in front of the airbag 92 toward theside bracket 24 a, which is on the inner side in the vehicle-widthdirection. The tensile members 90 b are inserted into the airbag 92 fromthe front side of the airbag 92 at substantially the midpoint betweenthe side brackets 24 a and 24 b. Second ends of the tensile members 90 bare fixed to side portions 92 b of the airbag 92 on the inner side inthe vehicle-width direction.

A one-way clutch 94 having an annular shape is disposed at crossingportions of the tensile members 90 a and 90 b, which is located in frontof the airbag 92. The tensile members 90 a and 90 b extend through theone-way clutch 94. The one-way clutch 94 freely allows the tensilemember 90 a and 90 b to pass therethrough in a direction from one endthereof to the other but does not allow the tensile members 90 a and 90b to pass therethrough in the opposite direction.

With this structure, because the airbag 92 is located between theelastic support members 27 and the back side of the seat back 20, whenthe airbag 92 deploys, the elastic support members 27 serve asreaction-force-receiving members as illustrated in FIG. 22, and theairbag 92 deploys in the backward direction of the seat back 20.

At the same time, the tensile members 90 a and 90 b are pulled by aforce that is generated as the airbag 92 deploys in the width directionof the seat back 20, so that the tensile members 90 a and 90 b becomestretched. Then, the airbag 92 receives a reaction force from thetensile member 90 a and 90 b, which has become stretched. Therefore, thedeployment of the airbag 92 in a direction toward the back side of theseat back 20 is restrained, and the position of the deployed airbag 92is controlled to be located between the side brackets 24 a and 24 b.

As a result, the position of the deployed airbag 92 can be controlled byusing a simpler structure, which includes the tensile members 90 a and90 b for floatingly supporting the airbag 92.

Referring to FIGS. 23A to 25B, a modification of the lumbar supportaccording to the fifth example will be described below. FIG. 23A is apartially cutaway rear perspective view of a lower part of a vehicleseat 70 according to the modification of the fifth example of thepresent invention, and FIG. 23B is a cross-sectional view of the lowerpart of the vehicle seat 70 taken along line XXIIIB-XXIIIB of FIG. 23A.FIG. 24A is a cross-sectional view illustrating an operation of a lumbarsupport when the lumbar support receives a load from the front side ofthe vehicle, and FIG. 24B is a partial enlarged view of a region XXIVBof FIG. 24A. FIG. 25A is a cross-sectional view of a seat backillustrating an operation of the vehicle seat 70 according to thepresent modification when a collision occurs, and FIG. 25B is a partialenlarged view of a region XXVB of FIG. 25A.

As illustrated in FIGS. 23A and 23B, in the vehicle seat 70 according tothe present modification, the overall structure of the seat back 20,excluding the structure of reaction-force-receiving members and thestructure of the airbag, is the same as that of the fifth example.Therefore, detailed description of the overall structure will beomitted.

As in the fifth example (see FIG. 17), the elastic support members 72are two S-springs made of metal wires. The elastic support members 72extend between side brackets 24 in an upper part of a substantiallyrectangular region R surrounded by the upper cross member 25, the sideframes 23, the side brackets 24, and the lower cross member 26.

In the present modification, as illustrated in FIGS. 23A and 23B, alumbar support 100 is a plate-shape member including a resin plate 100 aand strip-shaped plates 100 b that are continuously affixed to a backsurface of the resin plate 100 a. The resin plate 100 a has asubstantially rectangular shape in a rear view and has a flexibility toa certain degree. The plates 100 b (each of which is smaller than theresin plate 100 a) are stretchable in the height direction. The lumbarsupport 100 is supported by tension springs 76, which are hooked toU-shaped hooks 100 d disposed on side portions 100 c and U-shaped hooks24 c disposed on the side brackets 24.

In the present modification, the plates 100 b are disposed with nodistances therebetween. However, as described below, by adjusting thedistances between the plates 100 b, it is possible to set the amount bywhich the lumbar support 100 can be deformed so as to protrude in theforward direction of the vehicle.

In the present modification, an airbag 102 is folded into a flatrectangular shape corresponding to the substantially rectangular regionR in a rear view and is disposed in a deflated state behind the elasticsupport members 72 and the lumbar support 100.

With this structure, as illustrated in FIG. 24A, while the vehicle istravelling, the lumbar support 100 receives a load F1 generated by theoccupant Pf in the front seat 10, who is leaning on the seat back 20,and becomes slightly warped due to the load F1 so as to conform to theshape of the seat pad 28 that is deformed by receiving the load F1 andso as to protrude in the backward direction of the vehicle. Asillustrated in FIG. 24B, the lumbar support 100 can be deformed in thisway because gaps 104 are formed between adjacent plates 100 b as theresin plate 100 a, which has a certain degree of flexibility, becomesdeformed.

When the airbag 102 deploys, the airbag 102 is located between theelastic support members 72 and the back side of the seat back 20 of thelumbar support 100. Therefore, as illustrated in FIG. 25A, the elasticsupport members 72 and the lumbar support 100 function asreaction-force-receiving members, and the airbag 102 deploys toward theback side of the seat back 20.

At this time, as illustrated in FIG. 25B, the lumbar support 100receives from the airbag 102 a force oriented in the forward directionof the vehicle. However, because adjacent plates 100 b interfere witheach other, the lumbar support 100 does not become deformed so as toprotrude in the forward direction of the vehicle.

In other words, in a normal state, the lumbar support 100 serves toimprove the usability of the seat pad 28 by becoming warped and deformedso as to protrude backward by receiving the load F1 from the front sideof the vehicle. When the airbag 102 deploys, the lumbar support 100effectively serves as a reaction-force-receiving member that causes theairbag 102 to deploy in the backward direction of the vehicle.

Seventh Example

Referring to FIGS. 26 to 28, a vehicle seat according to a seventhexample of the present invention will be described. FIG. 26 is alongitudinal sectional view of a vehicle seat 110 according to theseventh example. FIG. 27 is a partially cutaway rear perspective view ofthe vehicle seat 110 according to the seventh example. FIG. 28illustrates how the vehicle seat 110 according to the seventh exampleoperates when a collision occurs.

The seventh example differs from the fourth example in that a floatingmember is flexibly supported through an elastic support member at aposition in front of the airbag 30. This difference will be describedbelow.

As illustrated in FIG. 26, in the seventh example, elastic supportmembers 112 are tension springs, each made of a metal wire, that arehooked to U-shaped hooks 114 b disposed on a side portion 114 a offloating member 114 and U-shaped hooks (not illustrated) disposed on theside brackets 24. Three elastic support members 112 radially extend fromthe central position of the floating member 114 to each of the sidebrackets 24. Instead of the tension spring, S-springs or the like may beused as the elastic support members 112.

As illustrated in FIG. 26, the floating member 114 has a substantiallyrectangular plate-like shape in a plan view. In the seventh example, thefloating member 114 is made of a cured synthetic resin. However, thefloating member 114 may be made of a flexible fabric or a net. Eventhrough the floating member is flexible, the elastic support members112, which extends radially between the floating member and the seatback frame 21, can hold the floating member to maintain a flat shape.

In the seventh example, the elastic support members 112 and the flatplate-like floating member 114 serve as a lumbar support. The floatingmember 114 presses the upper body of the occupant Pf forward through aseat pad 28 (described below), so that the occupant Pf (driver) candrive the vehicle in a natural position. Moreover, by appropriatelyadjusting the position of the flat plate-shaped floating member in theheight position, the lumbar support helps the spine of the occupant Pfto maintain an inverted-S-shaped gentle curve and reduces strain on theback of the driver during a long-hour driving.

The seat pad 28, which is made of urethane foam or the like, is disposedon the front side of the floating member 114. The airbag 30, which is ina deflated state and folded in a flat rectangular shape, is disposedbehind the floating member 114.

With such a structure, the seat back 20 is capable of elasticallysupporting the upper body, in particular, the chest of the occupant Pf,from behind.

For example, the back surface of the airbag 30 is supported by thecovering 41 or the like in the seat back 20 through engagement units(not illustrated) in such a way that the airbag 30 can deploy. The frontsurface of the airbag 30 is engaged with a back surface 114 c of thefloating member 114 in such a way that the airbag 30 can deploy. Asdescribed below, the airbag 30 includes a cylindrical inflator 29, whichgenerates a gas that is used to deploy the airbag 30. The airbag 30instantaneously deploys two-dimensionally when the inflator 29discharges the gas.

Accordingly, as illustrated in FIGS. 26 and 27, the airbag 30, which hasa substantially rectangular flat shape in a deflated state, is disposedin a space in the seat back 20 between the floating member 114 and thecovering 41. When the airbag 30 deploys, the seat back 20 covers thefront side of the airbag 30 with the floating member 114, which isflexibly supported by the elastic support members 112, and flexiblemembers, including the seat pad 28 and the covering 41. Moreover, theseat back 20 covers the back side of the airbag 30 with the covering 41,which is made of a flexible material.

When a vehicle including the vehicle seat 110 according to the seventhexample collides with another vehicle coming from behind and therear-end collision sensor 51 predicts a rear-end collision having apredetermined impact load or more, the controller 50 outputs a drivesignal to the inflator 29, and the inflator 29 discharges an inflationgas. Thus, as illustrated in FIG. 28, the airbag 30 deploysinstantaneously in a region between the floating member 114 and the backside of the seat back 20.

As the airbag 30 deploys, the elastic support members 112, the floatingmember 114, the seat pad 28, the covering 41, and the like, which aremade of flexible materials and which cover the front side of the airbag30, become deformed slightly in the forward direction of the vehicle asillustrated in FIG. 28. The covering 41, which is made of a flexiblematerial and which covers the back side of the airbag 30, protrudesconsiderably in the backward direction of the vehicle.

As in the fourth example, with the vehicle seat 110 according to theseventh example, due to deformation of the flexible members or flexiblematerials in front of and behind the airbag 30, the airbag 30 can deployby a sufficiently large deployment amount E in the front-back direction,and the seat back 20 provides a large impact absorbing distance in thefront-back direction of the vehicle.

In other words, as illustrated in FIG. 28, the covering 41 on the frontside of the seat back 20, the seat pad 28, the floating member 114flexibly supported by the elastic support members 112, and the deployedairbag 30 elastically receive backward movement of the upper body of theoccupant Pf in the vehicle seat 110 (front seat) due to an impact of arear-end collision. Therefore, the upper body of the occupant Pf in thevehicle seat 110 (front seat) is protected from an impact that occurswhen the upper body is pressed against the seat back 20 due to therear-end collision.

An occupant Pr in the rear seat is pressed against the rear seat 60 dueto an impact of the rear-end collision and then moved forward due to arebound. A knee of the occupant Pr in the rear seat, which is movedforward due to the rebound, is elastically received by the covering 41on the back side of the seat back 20 and the deployed airbag 30.Therefore, the upper body of the occupant Pf in the vehicle seat 110(front seat) is protected from an impact of the knee of the rear seatoccupant Pr.

At this time, the airbag 30 deploys stably in the seat back 20, which islocated in front of and behind the upper body of the occupant Pf in thevehicle seat 110, while being restrained to a certain degree by theinner shape of the seat back 20. Therefore, the airbag 30 can reliablyreceive backward movement of the upper body of the occupant Pf, absorban impact due to forward movement of the knee of the occupant Pr in therear seat, and reliably protects the occupant Pf.

Protection of the occupant Pf is performed by using the dispositions ofthe airbag 30, which deploys in the seat back 20, and flexible materials(that is, the covering 41, the seat pad 28, the floating member 114flexibly supported by the elastic support members 112, and the like) infront of and behind the airbag 30. As a result, the structure isconsiderably simplified.

Moreover, because the inflator 29 is attached to the floating member114, which is disposed within the seat back frame 21, with a centralportion of the front surface of the airbag 30 therebetween, the inflator29 can be located at substantially the center of the deployed airbag 30in the width direction and in the height direction. As a result, a gascan flow in radial directions into the airbag 30 from the centralposition, and the airbag 30 can deploy rapidly and stably in a state inwhich the entirety of the airbag 30 is balanced.

In addition, with such dispositions, the inflator 29 can be reliablyprotected from an impact due to a collision, and the gas can flow intothe airbag 30 in a direction toward the knee of the occupant Pr in therear seat. Therefore, the occupant Pf in the front seat can be protectedmore appropriately.

Because the floating member 114 is supported by radially extendingsprings, the floating member 114 can appropriately receive a reactionforce generated when the airbag 30 deploys (in other words, movement ofthe floating member 114 in the height direction and the width directionof the seat back when the floating member 114 receives the reactionforce can be strongly suppressed). Therefore, the airbag 30 can deploybackward more stably.

The floating member 114, which is a flat plate-shaped member extendingin a direction in which the seat back 20 extends, that is, in adirection substantially parallel to the width direction, can be disposedcompactly between the airbag 30 and the seat pad 28. Accordingly, alarge airbag deployment space can be provided behind the floating member114.

The present invention is not limited to the examples described above,and the examples can be modified within the spirit and scope of thepresent invention. For example, in contrast to the fourth example, thereaction-force-receiving members may be components of the seat backframe 21, such as the upper cross member 25, the lower cross member 26,or the like.

To be specific, for example, the airbag 30 may be attached to the uppercross member 25 and the airbag 30 may be disposed between the uppercross member 25 and the back side of the seat back 20. In this case,when the airbag 30 deploys as a gas flows from the inflator from theupper cross member 25 side, the airbag 30 receives a reaction force fromthe upper cross member 25 and can deploy backward and downward in theseat back 20. With this structure, an impact applied to the back side ofthe seat back 20 from behind and below can be effectively absorbed.

As heretofore described, by appropriately disposing thereaction-force-receiving members and the airbag, the airbag can deployin a direction facing a direction in which an impact is applied, so thatsuch an impact can be more effectively absorbed.

For example, in the seventh example, the elastic support members 112extend between side brackets 40 via the floating member 114.Alternatively, the elastic support members 112 may extend between theupper cross member 25 and the lower cross member 26 via the floatingmember 114.

The vehicles of the examples described above each have the vehicle seat(front seat) and the rear seat. However, it is not necessary for thevehicle to have a rear seat. For example, a cargo bed may be disposedbehind the vehicle seat. Also in this case, when a cargo on the cargobed moves forward due to a collision of the vehicle, the airbag 30deploys and protects an occupant in the vehicle seat from an impact thatis generated when the cargo collides with the back surface of the seatback 20.

What is claimed is:
 1. A vehicle seat, comprising: a seat back; and anairbag that deploys in the seat back, wherein the airbag deploys in theseat back in such a way that, after having deployed, the airbagelastically supports an upper body of an occupant and elasticallyreceives an impact force applied to a back surface of the seat back, andwherein, after having deployed, the airbag has such a shape that adeployment amount, in a front-back direction, of the airbag near a sideof the seat back is greater than that near a center of the seat back. 2.The vehicle seat according to claim 1, wherein, after having deployed,the airbag has such a shape that a deployment amount, in the front-backdirection, of the airbag near an outer side of a vehicle is greater thanthat near an inner side of the vehicle.
 3. The vehicle seat according toclaim 1, wherein, after having deployed, the airbag has such a shapethat a deployment amount, in the front-back direction, of the airbagnear an inner side of a vehicle is greater than that near an outer sideof the vehicle.